Adipic acid as a tableting lubricant

ABSTRACT

AN IMPROVEMENT IN THE PROCESS OF COMPRESSING POWDERED TABLETABLE COMPOSITIONS IS ACHIEVED BY MIXING ADIPIC ACID WITH SAID COMPOSITION PRIOR TO COMPRESSION. THE ADIPIC ACID ACTS AS A SURFACE LUBRICANT AND AS AN INTERNAL COMPRESSION LUBRICANT FOR SAID TABLETABLE COMPOSITIONS. THE POWDERED TABLETABLE COMPOSITIONS LUBRICATED WITH ADIPIC ACID CAN BE THOSE INTENDED FOR INTERNAL EMPLOYMENT, SUCH AS FOR ALKALIZING OF THE STOMACH, OR INTENDED FOR EXTERNAL USE, SUCH AS FOR GENERAL CLEANING OF SOLID SURFACES.

United States Patent O 3,584,099 ADIPIC ACID AS A TABLETING LUBRICANT George Carr Hoss, Elkhart, Ind., assignor to Miles Laboratories, Inc., Elkhart, Ind.

No Drawing. Original application July 7, 1969, Ser. No. 839,714, now Patent No. 3,506,756, dated Apr. 14, 1970. Divided and this application Dec. 29, 1969, Ser- No. 1,922

Int. 'Cl. A613 3/10; A611 13/00 US. Cl. 264-120 6 Claims ABSTRACT OF THE DISCLOSURE This is a division of application Ser. No. 839,714, filed July 7, 1969, now U.S. Pat. No. 3,506,756.

BACKGROUND OF THE INVENTION This invention relates to a tableting lubricant which can be mixed with a powdered tabletable composition to aid during the compression thereof into tablets, and particularly, to the use of adipic acid as a lubricant.

Tableting lubricants perform the general functions of providing (1) surface lubrication for the punch and die surfaces which come into contact with one another and with the compressed composition and (2) internal compression lubrication in order to lend pliability to the composition being compressed. Both of these lubrication functions must be satisfied if the powdered tabletable composition of interest is to be tableted commercially on tableting machines operated at high speeds. Some prior lubricants have provided only one of these two necessary lubrication functions and hence have necessitated joint use with another lubricant. A general problem with these prior lubricants has been their insolubility. This causes a tablet formed from an otherwise soluble composition to exhibit the appearance of a clouded suspension rather than a clear solution when dissolved in water. Talc and magnesium stearate are examples of such lubricants. Other lubricants are precluded in one or more marketing areas because of their toxicity. Examples of such lubricants are boric acid, benzoic and polyethylene glycol. Some tableting lubricants such as sodium benzoate have therapeutic action and therefore alter the pharmacological acceptability of tablets in which they are included.

SUMMARY OF THE INVENTION The adipic acid tableting lubricant can be used with a wide range of powdered tabletable compositions to allow high speed tableting thereof. While various amounts of adipic acid can be mixed with such compositions depending upon the presence therein of ingredients which impart some lubrication and upon the tableting speed desired, it is usually sufiicient to use about at least adipic acid based on the total weight of the composition being tableted when no other lubricants are used. If desired, adipic acid may be used in larger amounts, approaching the total tablet weight, since it is cohesive when compressed.

Adipic acid exists naturally as minute, colorless, monoclinic prisms which permit use according to the present invention with out further modification. If desired, these small prisms can be comminuted to any desired fineness.

Mesh sizes of 40 and finer are particularly preferred for use with most powdered compositions. Adipic acid is characterized by its low toxicity and hence it may be used for tablets which are intended to be taken internally.

The tabletable compositions which can be lubricated for tableting with adipic acid can, for example, be any compositions Which are cohesive enough when compressed to form and retain a tablet shape. Such compositions can be composed of powdered detergents, disinfectants, germicides and/or abrasives which disintegrate when placed in Water to form cleaning solutions of various types. Inclusion of quaternary compounds, such as cotyl pyridinium chloride, is particularly useful when cleaning tablets are to be produced.

The preferred com-positions, however, are effervescent mixtures comprised of an alkali metal carbonate or bicarbonate and an acid such as malic, citric or tartaric acids which are capable of rapidly releasing carbon dioxide upon addition of water thereto. When the carbon dioxide has been released, the solution formed is useful for its alkalizing properties when taken orally.

The compositions can also include at least one therapeutic agent, water-soluble excipients, and any necessary coloring or flavoring agents, diluents, binders, or disintegrators. In such compositions the therapeutic agent may be acetylsalicyclic acid, acetyl p-aminophenol or other suitable analgesic.

If necessary, binders may be added to the base composition to promote cohesion. All of such compositions are tabletable in that they are cohesive when compressed. However, without a lubricant most of such compositions can be tableted only by hand, since they cause binding and scoring of the punches and dies of power driven tableting machines. In order to attain commercial production speeds a tableting lubricant must be employed to reduce surface friction and internal compression friction.

The adipic acid of the present invention may be used as the sole lubricant or may be employed in conjunction with another lubricant included in the tabletable composition. More particularly the adipic acid lubricant can be substituted for various materials which function as tablet lubricants during compression.

In effervescent tablets adipic acid provides the additional effect of taking part in the effervescent action. When the adipic acid does form part of the effervescent couple it is neutralized to a metal salt, if a sufiicient amount of an alkaline material is employed, and in such form is even more highly soluble than is the free adipic acid. Hence, when greater solubility than that for free adipic acid is desired, a source of alkali metal ions may be included in the pharmaceutical composition, whereby upon dissolution of the composition in water the alkali metal salt of adipic acid is formed and any solubility limitations of adipic acid are obviated. Generally, however, this is not necessary due to the fact that the adipic acid is used in amounts low enough so that the volume of water normally used for dissolution of the tablets is sufficient to dissolve all of the adipic acid employed.

Amounts of at least about 5% adipic acid based on the total Weight of the lubricated tabletable composition are generally suflicient to allow high speed tableting when adipic acid is used as the sole lubricant. When it is used as one of at least two tableting lubricants a proportionately smaller amount may be used. Amounts of about from 5% to 15% adipic acid allow tableting of effervescent mixtures at rates up to about 5000* tablets per minute on rotary tablet machines containing 47 punch and die sets. Each punch and die set produces approximately 106 tablets per minute in such machines. On a rotary machine containing 33 punch and die sets, tablets may be compressed at a rate of 76 tablets per minute per set for a total production of about 2500 tablets per minute.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT In the following example the concentrations of components are stated as weight percent of the weight of lubricated composition as tableted.

Component: 7 Amount, grams Sodium bicarbonate 1674 Citric acid (anhydrous) 1000 Adipic acid 320 Calcium hydrogen orthophosphate 205 Magnesium oxide 4 Sodium cyclohexylsulfamate Sodium saccharinate 2 Peppermint oil encapsulated in gum acacia 16 The above components in the amounts stated were dried, reduced to 30 mesh screen size and thoroughly mixed. The adipic acid in the composition was present in a concentration of 9.8 weight percent.

The resulting mixture was placed in a hopper of a handoperated punch rotary tableting machine from which the mixture was fed to the dies of the punch and die sets of the machine. The compression pressure was 11 kg. The tablets produced were 0.158 in. thick and weighed approximately 3.2 g. each.

Upon completion of the run the tablets were found to be smooth surfaced and elegant in appearance. Upon immersing in 120 ml. of water at C. a tablet quickly elfervesced and dissolved to give a sparkling clear solution of pH 5.8 with no sediment.

I claim:

1. In the process of imparting free-flowing dry powdery lubrication for the surfaces of the punch and die walls of high-speed power-driven machines producing tablets by compressing a dry, free flowing powdered tabletable material otherwise causing binding and scoring of the punches and dies of power-driven tableting machines, aiding the flow of such material into the dies of tableting machines and, upon compression and subsequent ejection of the tabletable material, aiding in maintaining the punch and die surfaces free from any retained material which would otherwise, if allowed to build up, cause poor tableting characteristics, the improvement comprising homogeneously intermixing with, said material prior to compression thereof, as the essential lubricant, a dry mixable free flowing lubricant powder comprising adipic acid, compressing the free-flowing, dry, powdery, homogeneous intermixture into cohesive tablets in the punch and dies of a high-speed power driven tablet machine, ejecting the tablets from the dies, repeating said compressing and ejecting steps at optimum high-speed tableting rates permitted for each punch and die set in such machine, with the result that the punch faces and die wall surfaces of high speed power-driven tablet machines are free from any visible retained material which would otherwise, if allowed to build up, cause poor tableting characteristics.

2. The process of claim 1 wherein said powdered tabletable composition is an adipic acid-free effervescent mixture of a base and an acid.

3. The process of claim 1 wherein there is present at least about 5% adipic acid based on the total weight of said adipic acid and said powdered tabletable composition.

4. The process of claim 3 wherein said tablet is compressed in a high speed cycle and said powdered tabletable composition is an adipic acid-free effervescent mixture of a base and an acid.

5. The process of claim 1 wherein said powdered tabletable composition includes a therapeutic agent.

6. The process of claim 1 wherein said adipic acid is present in an amount of about from 5% to 15% based on the total weight of said adipic acid and said powdered tabletable composition and wherein said composition is an adipic acid-free effervescent mixture of a base and an acid.

References Cited UNITED STATES PATENTS 2,448,524 9/1948 Gentner 117-100 2,971,848 2/1961 Polya 99-141 2,977,300 3/1961 Bergen et al. 252--18 2,977,301 3/1961 Bergen et a1. 252--18 3,105,792 10/1963 White 42444 3,136,692 6/1964 Bandelin 42444 3,355,392 11/1967 Cantor et al. 252-99 FOREIGN PATENTS 1,074,958 2/ 1960 Germany. 1,075,255 2/ 1960 Germany.

845,628 8/ 1960 Great Britain. 1,165,098 9/19'69 Great Britain.

SHEP K. ROSE, Primary Examiner U.S. Cl. X.R. 

